Method and apparatus for determining type of digital versatile disc

ABSTRACT

A method and an apparatus for determining types of digital versatile discs (DVDs) are provided. The method includes setting related parameters, acquiring a wobble signal from a DVD, setting a frequency dividing factor, and dividing the frequency of the wobble signal by the frequency dividing factor. Then, the time required for the digital versatile disc to spin one round, which is driven by a spindle motor of a disc player, is set as a unit time to calculate the frequency of the frequency-divided wobble signal. Finally, the type of the digital versatile disc is determined according to the frequency of the wobble signal.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefits of U.S. provisional application titled “NEW METHOD OF IDENTIFYING ROM/R/RW TYPE OF DVD DISC (USING TE SIGNAL, RECD SIGNAL AND RFLVL SIGNAL)” filed on May 25, 2004, Ser. No. 60/574,665. All disclosure of this application is incorporated herein by reference. This application also claims the priority benefit of Taiwan applications serial no. 93130202, filed on Oct. 6, 2004, serial no. 93127819, filed on Sep. 15, 2004. All disclosure of these Taiwan applications is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and an apparatus for determining types of digital versatile discs, and more particularly to a method and an apparatus for determining DVD-ROM, DVD− and DVD+ types of digital versatile discs.

2. Description of the Related Art

Digital versatile discs (DVDs) available in the market include a read-only-memory (DVD_ROM) type, from which data can only be read, and another type in which data can be written/burned. The data-burnable DVDs include DVD− and DVD+ based on different specifications. Most DVD players are compatible in different specifications. Therefore, how to determine a type of a disc has become an essential technique.

The conventional method is to use position data contained in pre-groove wobble signals to determine the types of DVDs. According to the specifications of DVDs, DVD-ROM does not contain wobble signals. In contrary, DVD− and DVD+ contain not only normal tracks but also wobble signals. The source of these signals is shown in FIG. 1. When a disc spins in a DVD player, the pick-up head 101 slides outwardly along the track 102 as shown in FIG. 1. Photo diodes of the pick-up head 101 are arranged as shown in FIG. 1. These areas A, B, C and D sense signals with different intensities. Accordingly, wobble signals can be generated according to the following formula: G×[g1×(A+D)−g2×(B+C)]

Wherein, G, g1 and g2 are adjustable gains.

DVD− and DVD+ have position data which are contained in wobble signals and can be decoded by logic operational circuits in order to obtain the present position data. FIG. 2 is a schematic drawing showing a wobble signal of DVD+. The wobble signal 201 includes plural phase change regions 202. The position data can be obtained from the wobble signal 201 after the wobble signal 201 is decoded by the logic operational circuit. FIG. 3 is a schematic drawing showing a wobble signal of DVD−. The wobble signal 301 includes plural land per-pits 302. Similarly, the position data can be obtained after the wobble signal 301 is decoded by the logic operational circuit. From FIGS. 2 and 3, it can be seen that for different wobble signals of DVD+ and DVD−, the decoding functions of the logic operational circuits are also different. Accordingly, they can be used to determine the types of DVDs.

FIG. 4 is a flowchart showing a conventional method for determining a type of a digital versatile disc. First, in step 402, it is assumed that the loaded disc is DVD+, and the parameters for DVD+ are set. In step 404, determining whether the present position data are successfully accessed. If the data can be accessed, it is determined the disc is DVD+ in step 406. If not, it is assumed the disc is DVD− in step 408, and the parameters for DVD− are set. In step 410, determining whether the present position data are successfully accessed again. If the data can be accessed, it is determined the disc is DVD− in step 412. If not, it is determined the disc is DVD-ROM in step 414.

The disadvantage of this method is that the parameters of DVD+ and DVD− must include parameters of most discs, especially for burned discs. Since the quality of position data on burned discs become worse, false determination is very likely to occur. Accordingly, a new method is desired to resolve the issue and enhance the probability of correctly determining the types of DVDs.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method for determining a type of a digital versatile disc to overcome the false determination defect of the conventional technology.

The present invention is also directed to an apparatus for determining a type of a digital versatile disc to overcome defects of the conventional technology and enhance the probability of correctly determining the type of digital versatile discs.

In order to achieve the above and other objects, a method for determining a type of a digital versatile disc is provided according to an embodiment of the present invention, which mainly comprises setting relative parameters, acquiring a wobble signal from a digital versatile disc, setting a frequency dividing factor, and dividing the frequency of the wobble signal with the frequency dividing factor. Then, the time required for the digital versatile disc to spin one round, which is driven by a spindle motor of a disc player, is set as a unit time to calculate the frequency of the frequency-divided wobble signal. Finally, the type of the digital versatile disc is determined according to the frequency of the wobble signal.

In order to achieve the above and other objects, an apparatus for determining a type of a digital versatile disc is provided according to an embodiment of the present invention. The apparatus comprises an acquisition apparatus, which acquires a wobble signal from a digital versatile disc, digitalizes the wobble signal and outputs the digitalized wobble signal; and a determining apparatus, which is coupled to the acquisition apparatus, determining and outputting the type of the digital versatile disc according to the frequency of the wobble signal. Wherein, the determining apparatus further comprises a filter coupled to an input terminal of the determining apparatus, used for receiving the digitalized wobble signal, filtering noises in the wobble signal, and outputting the filtered wobble signal; a frequency counter coupled to the filter, calculating and outputting the frequency of the wobble signal according to the filtered wobble signal; and a determining device coupled to the frequency counter, used for determining and outputting the type of the digital versatile disc according to the frequency of the wobble signal.

In the present invention, the type of the digital versatile disc is determined according to the frequency of the wobble signal, rather than the position data contained in the wobble signal in the conventional technology. Disadvantages in the conventional technology, such as false determination and incompatibility between position data and different disc players, can be avoided. Accordingly, the probability of correctly determining the type of the digital versatile disc can thus be enhanced.

The above and other features of the present invention will be better understood from the following detailed description of the embodiments of the invention that is provided in communication with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing showing the source of a wobble signal.

FIG. 2 is a schematic drawing showing a wobble signal of DVD+.

FIG. 3 is a schematic drawing showing a wobble signal of DVD−.

FIG. 4 is a flowchart of a conventional method for determining a type of a digital versatile disc.

FIG. 5 is a configuration showing ranges of wobble signal frequencies of three digital versatile discs for an apparatus for determining a type of a digital versatile disc according to an embodiment of the present invention.

FIG. 6 is a schematic drawing showing an apparatus for determining a type of a digital versatile disc according to an embodiment of the present invention.

FIG. 7 is a flowchart of a method for determining a type of a digital versatile disc according to an embodiment of the present invention.

DESCRIPTION OF SOME EMBODIMENTS

The present invention uses frequencies of wobble signals of digital versatile discs to identify three types of the digital versatile disc, DVD read-only-memory (DVD-ROM), DVD−, and DVD+. The following is description of the method and apparatus for determining types of digital versatile discs according to the present invention.

Different types of DVDs have different frequencies of wobble signals. When the data transfer rate is 1×1349 KB/s, and the time required for the disc to spin a round, which is driven by a spindle motor of a disc player, is set as a unit time, the frequency of the wobble signal of DVD+ is 817.5 KHz, the frequency of the wobble signal of DVD− is 140.6 KHz, and DVD-ROM does not contain any frequency of the wobble signal thereon and thus has a frequency 0. The difference among these frequencies is the basis for determining types of digital versatile discs in the present invention.

For disc players, the actual frequency calculation is more complicated. Most of the disc players use the constant angular velocity (CAV) mode. The data transfer rates at the innermost circle and the outermost circle are apparently different. That is, frequencies of wobble signals of DVD− and DVD+ are within a range, rather than constant values. In the logic circuit of analyzing the wobble signals, the step of frequency dividing may be applied. The step of frequency dividing is used to reduce the frequency of the wobble signal with a frequency dividing factor. For example, if the frequency dividing factor is ½, the frequency of the frequency-divided wobble signal is a half of the frequency of the original wobble signal. Accordingly, the frequency of the wobble signal at the innermost circle of the DVD+ is:

-   817.5 KHz×data transfer rate of the innermost circle×frequency     dividing factor. The frequency of the wobble signal at the outermost     circle of the DVD+ is: -   817.5 KHz×data transfer rate of the outermost circle×frequency     dividing factor. Accordingly, the frequency of the wobble signal at     the innermost circle of the DVD− is: -   140.6 KHz×data transfer rate of the innermost circle×frequency     dividing factor, and the frequency of the wobble signal at the     outermost circle of the DVD− is: -   140.6 KHz×data transfer rate of the outermost circle×frequency     dividing factor.

In this embodiment, the disc player spins the disc in the 4X CAV mode. As a result, the data transfer rate of the innermost circle is 2X, the data transfer rate of the outermost circle is 4X, and the frequency dividing factor is ½. After a simple calculation, the range of the frequency of the DVD+ wobble signal is 800 KHz-1.6 MHz, the range of the frequency of the DVD− wobble signal is 140 KHz-280 KHz, and the frequency of the DVD-ROM is 0 as shown in FIG. 5. Actually, the DVD-ROM, due to errors in real operations, may still generate some frequency in the wobble signal. The minor frequency of the wobble signal, however, will not affect determinations in the present invention.

It can be observed in FIG. 5, under a constant spinning speed, the frequency ranges of the three discs do not overlap, and in fact the frequency ranges are very different from each other. The false determination resulting from accessing different wobble signal frequencies at different locations can be avoided.

The present embodiment includes the step of frequency dividing. All parameters and details have been modified based on requirements of frequency dividing, which actually can be skipped. Without frequency dividing, the effect of the dividing factor in the frequency range of the wobble signal in FIG. 5 should be removed. In the schematic drawing of FIG. 6, devices related to frequency dividing should be removed. In the flowchart of FIG. 7, steps related to frequency dividing should also be skipped. One of ordinary skill in the art can easily modify the present invention after reading the description of this embodiment.

FIG. 6 is a schematic drawing showing an apparatus according to an embodiment of the present invention. As shown in FIG. 6, a acquisition apparatus 601 acquires a wobble signal 607 from the digital versatile disc, digitalizes and outputs the wobble signal 607 to a determining apparatus 602. The determining apparatus 602, according to the frequency of the wobble signal 607, determines the type of the digital versatile disc and outputs a type signal 610.

The determining apparatus 602 comprises several devices. First, a filter 603 receives the digitalized wobble signal 607, filters noises in the wobble signal 607, and outputs the filtered wobble signal to a frequency divider 604. When noises are not so serious to cause false determination, the step of filtering the noises or the filter 603 can be skipped or removed. The frequency divider 604 divides the frequency of the wobble signal 607 by a preset frequency dividing factor, ½ in this embodiment, and outputs the frequency-divided wobble signal to the frequency counter 605.

The frequency counter 605 receives a spinning speed signal 609 transmitted from the spindle motor (not shown) of the disc player. According to the spinning speed signal 609 and the unit time for spinning one round of the digital versatile disc, which is driven by the spindle motor, the frequency counter 605 calculates the frequency of the frequency-divided wobble signal, and outputs the frequency to the determining device 606. A activation signal 608 is used to active the frequency counter 605. Finally, according to the frequency outputted from the frequency counter 605 and frequency ranges of these discs shown in FIG. 5, the determining device 606 determines the type of the digital versatile disc and outputs the type signal 610.

FIG. 7 is a flowchart showing a method according to an embodiment of the present invention. First, in step 702, relative parameters are set. In step 704, the wobble signal is obtained from the digital versatile disc. In step 706, the frequency dividing factor, ½ in the embodiment is set. In step 708, the frequency of the wobble signal is divided by the frequency dividing factor. Then, in step 710, the frequency of the frequency-divided wobble signal is calculated according to the unit time for spinning the digital versatile disc one round, which is driven by the spindle motor of the disc player.

After the frequency calculation, in step 712, the type of the disc is determined according to the frequency of the frequency-divided wobble signal. If the frequency is 0, it is determined that the type of the digital versatile disc is DVD-ROM in step 714. If the frequency falls between 140 KHz and 280 KHz, it is determined that the type of the digital versatile disc is DVD− in step 716. If the frequency falls between 800 KHz and 1.6 MHz, it is determined that the type of the digital versatile disc is DVD+ in step 718.

For digital versatile discs DVD+ or DVD−, frequency dividing factors which are frequently used are 2/23 or ½. That is, if the determination of the type of the digital versatile disc with one of these frequency dividing factors is false, another frequency dividing factor can be used.

It can be seen from the descriptions above that in the present invention, the type of the digital versatile disc is determined according to the frequency of the wobble signal, rather than the position data in the wobble signal in the conventional technology. Therefore, disadvantages of the conventional technology such as false determination and incompatibility between position data and different disc players can be avoided. The probability of correctly determining the type of the digital versatile disc can thus be enhanced.

Although the present invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be constructed broadly to include other variants and embodiments of the invention which may be made by those skilled in the field of this art without departing from the scope and range of equivalents of the invention. 

1. A method for determining the type of a digital versatile disc, comprising the steps of: (a) acquiring a wobble signal from a digital versatile disc; and (b) determining the type of the digital versatile disc according to the frequency of the wobble signal.
 2. The method of claim 1, wherein in step (b), the type of the digital versatile disc is determined according to a first frequency, a second frequency and a third frequency, and among a first type, a second type and a third type.
 3. The method of claim 2, wherein step (b) further comprises: if the frequency of the wobble signal is smaller than the first frequency, the type of the digital versatile disc being determined as the first type; if the frequency of the wobble signal is between the second frequency multiplying the data transmission rate of the innermost circle of the digital versatile disc, and the second frequency multiplying the data transmission rate of the outermost circle of the digital versatile disc, the type of the digital versatile disc being determined as the second type; and if the frequency of the wobble signal is between the third frequency multiplying the data transmission rate of the innermost circle of the digital versatile disc, and the third frequency multiplying the data transmission rate of the outermost circle of the digital versatile disc, the type of the digital versatile disc being determined as the third type.
 4. The method of claim 3, wherein the second frequency is 140.6 KHz, the third frequency is 817.5 KHz, the first type is DVD-ROM, the second type is DVD−, and the third type is DVD+.
 5. The method of claim 1, wherein step (b) further comprises: setting the time required for the digital versatile disc to spin one round driven by a spindle motor of a disc player as the unit time and calculate the frequency of the wobble signal.
 6. The method of claim 5, wherein step (b) further comprises: using a frequency dividing factor to divide the frequency of the wobble signal; and the frequency of the wobble signal calculated in step (b) is the frequency of the wobble signal after the frequency dividing.
 7. The method of claim 6, wherein step (b) further comprises: if the frequency of the wobble signal after the frequency dividing is smaller than the first frequency, the type of the digital versatile disc being determined as the first type; if the frequency of the wobble signal after the frequency dividing is between the second frequency multiplying the data transmission rate of the innermost circle of the digital versatile disc multiplying the frequency dividing factor, and the second frequency multiplying the data transmission rate of the outermost circle of the digital versatile disc multiplying the frequency dividing factor, the type of the digital versatile disc being determined as the second type; and if the frequency of the wobble signal after the frequency dividing is between the third frequency multiplying the data transmission rate of the innermost circle of the digital versatile disc multiplying the frequency dividing factor, and the third frequency multiplying the data transmission rate of the outermost circle of the digital versatile disc multiplying the frequency dividing factor, the type of the digital versatile disc being determined as the third type.
 8. The method of claim 6, wherein the frequency dividing factor is one of ½ and 2/23.
 9. An apparatus for determining the type of a digital versatile disc, comprising: an acquisition apparatus for acquiring a wobble signal from a digital versatile disc, digitalizing the wobble signal, and outputting the digitalized wobble signal; and a determining apparatus coupled to the acquisition apparatus, used for determining and outputting the type of the digital versatile disc according to a frequency of the wobble signal.
 10. The apparatus of claim 9, wherein the determining apparatus further comprises: a filter coupled to an input terminal of the determining apparatus, used for receiving the digitalized wobble signal, filtering noises in the wobble signal, and outputting the filtered wobble signal; a frequency counter coupled to the filter, used for calculating and outputting the frequency of the wobble signal according to the filtered wobble signal; and a determining device coupled to the frequency counter, used for determining and outputting the type of the digital versatile disc according to the frequency of the wobble signal.
 11. The apparatus of claim 10, wherein the frequency counter also receives an activation signal and determines when to start counting the frequency of the wobble signal according to the activation signal.
 12. The apparatus of claim 10, wherein the frequency counter also receives a spinning speed signal transmitted from a spindle motor of a disc player, and, based on the spinning speed signal, sets the time for the digital versatile disc to spin one round driven by the spindle motor of the disc player as the unit time and calculates the frequency of the wobble signal.
 13. The apparatus of claim 12, wherein the determining device determines the type of the digital versatile disc according to a first frequency, a second frequency and a third frequency, and among a first type, a second type and a third type.
 14. The apparatus of claim 13, wherein if the frequency of the wobble signal is smaller than the first frequency, the digital versatile disc is determined as the first type; if the frequency of the wobble signal is between the second frequency multiplying the data transmission rate of the innermost circle of the digital versatile disc, and the second frequency multiplying the data transmission rate of the outermost circle of the digital versatile disc, the digital versatile disc is determined as the second type; and if the frequency of the wobble signal is between the third frequency multiplying the data transmission rate of the innermost circle of the digital versatile disc, and the third frequency multiplying the data transmission rate of the outermost circle of the digital versatile disc, the digital versatile disc is determined as the third type.
 15. The apparatus of claim 14, wherein the second frequency is 140.6 KHz, the third frequency is 817.5 KHz, the first type is DVD-ROM, the second type is DVD−, and the third type is DVD+.
 16. The apparatus of claim 13, wherein the determining apparatus further comprises: a frequency divider coupled between the filter and the frequency counter, used for receiving the filtered wobble signal outputted from the filter, dividing the frequency of the wobble signal by a dividing frequency factor, and outputting the frequency-divided wobble signal to the frequency counter.
 17. The apparatus of claim 16, wherein the frequency dividing factor is one of ½ and 2/23.
 18. The apparatus of claim 16, wherein if the frequency of the wobble signal after the frequency dividing is smaller than the first frequency, the digital versatile disc is determined as the first type; if the frequency of the wobble signal after the frequency dividing is between the second frequency multiplying the data transmission rate of the innermost circle of the digital versatile disc multiplying the frequency dividing factor, and the second frequency multiplying the data transmission rate of the outermost circle of the digital versatile disc multiplying the frequency dividing factor, the digital versatile disc is determined as the second type; and if the frequency of the wobble signal after the frequency dividing is between the third frequency multiplying the data transmission rate of the innermost circle of the digital versatile disc multiplying the frequency dividing factor, and the third frequency multiplying the data transmission rate of the outermost circle of the digital versatile disc multiplying the frequency dividing factor, the digital versatile disc is determined as the third type. 